The great fish migration has begun

Rising sea temperatures are pushing shoals of fish hundreds of kilometers from their native grounds, with warm-water fish now landing in northern nets

By Robin McKie / The Guardian

It indicates that the UN Food and Agriculture Organization has seriously underestimated the world’s appetite for fish and miscalculated global annual catches. The UN agency — using figures provided by individual governments — had suggested that annual catches began rising significantly in the 20th century, peaked at 96 million tonnes in 1996 and have been declining slowly since then — largely due to the fact that fish stocks had been so seriously overfished.

Pauly and Zeller put the annual “peak fish” figure for 1996 at 130 million tonnes, saying that levels have fallen off far more dramatically and worryingly as stocks have become depleted at a rate that is far sharper than realized previously.

In other words, far more fish — millions of tonnes — is being taken from the seas than has been recorded by official statistics.

This extra annual catch is made up by small-scale and subsistence fisheries and fish thrown back in the sea as discards, Pauly and Zeller said.

What is particularly worrying about this discovery is the sharp rate of decline of fish catches in recent years. Despite sending out more boats, fitted with advanced fish detection technologies, fishermen are unable to catch as much as they used to.

Nor do Pauly and Ziller anticipate that it will stop.

“I expect a continued decline, because I don’t expect countries to realize the need to rebuild stocks,” Pauly told the Guardian. “I don’t see African countries, for example, rebuilding their stocks, or being allowed to by the foreign fleets that are working there, because the pressure to continue to fish is very strong. We know how to fix this problem, but whether we do it or not depends on conditions that are difficult.”

It is against this grim background that the world’s oceans are warming significantly, with temperature rises of several degrees being forecast by the end of the century.

Inexorably, fish stocks will be pushed further toward high latitudes, confusing attempts to manage and to protect them, while the makeup of local fisheries will undergo drastic changes. The stress on one of the world’s most important resources is going to be intense.